1. Field of the Invention
This invention relates to a flexible shaft coupling for transmission of high torque loads which is installed between a drive shaft and a driven shaft of general industrial machinery, automobiles, etc. in order to transmit torques while absorbing deflections between them.
2. Related Art Statement
For a flexible shaft coupling for transmission of high torque loads to be installed on drive shafts, etc. of automobiles, for instance, a coupling as shown in the accompanying FIG. 4 has been formerly known. This coupling is constructed of cylindrical drive side connecting elements (3) for holding therethrough bolts (2) secured to the rod end of a drive shaft (1) corresponding to an output shaft on the engine side and cylindrical driven side connecting elements (6) for holding therethrough bolts (5) secured to the rod end of a driven shaft (4) corresponding to a propeller shaft, both of which are arranged alternately in pairs along the circumference of the coupling. Pairs of adjacent connecting elements (3)(6) are interlinked by wrapping thereabout endless belts (8) of fiber bundles having elasticity which are formed by winding reinforcing cords (7) of polyester yarns in multiple plies and multiple rows and further coated peripherally with a rubber or synthetic resin material (9) whereby they are integrally fabricated into a ring-shaped coupling which is rectangular in cross-section. With a view toward preventing the wrapped portions of the fiber bundles from being rubbed against each other and the superposing arrangement of the reinforcing cords (7) from being disturbed, collars (10) which are press molded in the form of a disk having a L-shaped cross-section are press-fitted and held on the outer peripheries of the drive side connecting elements (3) and the driven side connecting elements (6).
Such type of couplings are disclosed, for example, in Japanese Utility Model Publication No. 56-35539 (1981), Japanese Utility Model (Unexamined) Publication No. 59-146623 (1984), etc.
In the flexible couplings having the known structure noted above, in case where high loads act upon the belts (8) of fiber bundles as a result of fluctuation in load on the drive shaft side (4), the bundles of reinforcing cords (7) are squashed in the radial direction and .spread in the axial direction to move the collars (10) outwardly and consequently, arrangement of the reinforcing cords (7) is disordered, causing them to relax. Thus, they were defective in that cord strength is diminished and efficiency of torque transmission is aggravated.
Further, in the event that the arrangement of the reinforcing cords (7) constituting the belts (8) of fiber cord bundles was changed, the odds are that the reinforcing cords (7) rub against one another owing to the fluctuation in torque. Hence, existing flexible couplings had to be replaced early in this respect.